Formulation and properties of a new cleaner double liquid alkali-activated grouting material

Abstract

Herein, a new cleaner double liquid alkali-activated grouting material (DLAG) was successfully developed, which could be applied similarly to cement by adding water. Desulphurisation gypsum (DG) was selected to activate ground granulated blast-furnace slag (GGBFS) and fly ash (FA) to completely replace cement. The optimum proportion of the basic materials and admixtures were determined by a series of orthogonal and single-factor controlled variable experiments. The mechanism for the strength enhancement of the materials was interpreted by microscopic experiments. The optimum proportion of the basic materials was determined that slurry A comprised of only GGBFS, whereas DG, FA, and metakaolin (MK), were present in a mass ratio of 6:3:1 in slurry B. The single slurry maintained good workability over a long period before mixing, and the fluidity of mixed slurry could be dynamically adjustable from 138 mm to 215mm. The strength of solidified specimens reached 45.7 MPa at 28 days curing time, which was 220% higher than that of Portland cement. Microscopic analyses showed that Al2O3 and SiO2 in the precursor materials were continuously dissolved and reorganised to produce hybridised phase gels (C, N)-A-S-H (calcium, sodium aluminium silicate hydrate), and also hydrated with Ca2+, SO42− provided by DG to produce ettringite and calcium silicate hydrate (C-S-H) in the alkaline environment. The size and content of hydration products gradually increased with increasing curing time and acted together to enhance the strength of solidified body. The proposed material can promote the development of alkali-activated technology in the field of special grouting materials.